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通过观察裂纹与断口形貌,结合第二相析出规律,分析了AMS 6308钢大规格棒材锻造开裂原因。结果表明:大锭型中Cu偏析导致钢热塑性变差是锻件开裂的主要原因。在钢锭加热时Cu元素偏析会析出大量低熔点富Cu相。高温下部分呈液膜状,随着富Cu液膜的浸润,造成晶界结合力下降。随后,钢的热塑性变差,在锻造应力的作用下产生裂纹并扩展。
By observing the crack and fracture morphology, combined with the precipitation law of the second phase, the reasons for the forging cracking of AMS 6308 steel large size bar were analyzed. The results show that the main reason for the cracking of the forgings is that the segregation of Cu in the ingot causes the decrease of the thermoplasticity of the steel. In steel ingot heating Cu segregation will precipitate a lot of low melting point rich Cu phase. Part of the liquid film under high temperature, with the infiltration of Cu-rich liquid film, resulting in decreased binding capacity of grain boundaries. Subsequently, the thermoplastic of steel deteriorates and cracks and expands under the action of forging stress.